In radio frequency applications, different multiple-input and multiple-output devices communicate with each other wherein a transmitter is used that comprises at least one transmission antenna. The signal transmitted by the transmitter is received by a receiver that comprises at least one receiving antenna for receiving the signal transmitted by the transmitter. Such a system is a conventional radio system which is also called singe-input and single-output (SISO) system.
It is further known that the capacity of the communication can be multiplied by using more than one transmission antenna and receiving antenna. Such a system is called multiple-input and multiple-output (MIMO) system. As multiple transmission and receiving antennas are used for communication, the signals transmitted via a first transmission antenna is received by all receiving antennas such that several data channels are formed for one transmission antenna. The same applies to the other transmission antennas. Thus, devices using MIMO technique can transmit and receive several data signals simultaneously via different data channels provided between the multiple transmission antennas and the multiple receiving antennas. Accordingly, the number of data channels increase with the number of transmitting and receiving antennas. Afterwards, the data signals received via the multiple data channels have to be recomposed wherein different techniques are known in order to sort the data received via these data channels.
For testing and calibration purposes; it is necessary to know the portion of a first data signal received by a first receiving antenna wherein the first data signal has been transmitted by a first transmission antenna. This also applies for the portion of a second signal transmitted by a second transmission antenna and received by a second receiving antenna and so on.
Usually, a wire has to be used which connects a certain transmission antenna with a certain receiving antenna such that information about the dedicated data channel can be gathered.
However, multiple-input and multiple-output devices as well as the corresponding systems are designed for wireless communication. Furthermore, each of the several antennas has to be connected with each other which requires a lot of manual work for setting up the test system. Thus, it would be desirable to provide a more reliable method and test system to test a multiple-input and multiple-output device.